futility: Merge Debug() into VB2_DEBUG()

Futility has two debug facilities: the Debug() function that can be
enabled by passing --debug on the command line, and the VB2_DEBUG()
macro (mostly in common code from the firmware/ directory that it
includes) which can only be enabled by passing DEBUG=1 at build time.
This is confusing and inconvenient, since you don't always want to
rebuild futility whenever you need that extra debug output and it's not
very obvious that you can get even more debugging beyond just passing
--debug.

This patch resolves the inconsistency by merging both facilities
together into a single VB2_DEBUG() that is output when passing --debug.
In order to make this work, we'll have to move the VBOOT_DEBUG #define
so that it only affects the stub implementation of vb2ex_printf(), and
any caller overriding the stub is in charge of their own destiny. This
should be okay since callers can still individually implement debugging
policy in their versions of vb2ex_printf() if they want to. (This may
have been useful to cut down the binary space for debugging strings, but
our firmware has always been unconditionally enabling VBOOT_DEBUG in the
past years, so that doesn't seem to be very important in practice.)

BRANCH=None
BUG=None
TEST=Ran futility --debug show, noticed I got all the extra keyblock
verification debug output I always wanted.

Change-Id: I9a5c205fc3673941b50f03f2a967b1be110a1555
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1504140
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
11 files changed